<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		 <script src="https://cdn.jsdelivr.net/npm/vue@2/dist/vue.js"></script>
		<title></title>
	</head>
	<body>
		
		<div id="example">
			{{a}}
		</div>
		
		<script type="text/javascript">
			var data = {a:1}
			var vm = new Vue({
				el:'#example',
				data:data
			})
			vm.$data === data
			vm.$el === document.getElementById('example')
			
			vm.$watch('a',function(newVaule,oldValue){
				
			})
			
		</script>
		
	</body>
</html>
